The present invention relates to a tubular plate for a wiper device as a support for at least one wiper bearing and a wiper drive.
Known wiper devices have a window wiper frame and several components mounted on it and including a wiper drive having an electric motor and a transmission, a drive shaft with a drive crank and drive rods, a wiper bearing, and driven shafts with driven cranks. The window wiper operates as a support and serves for mounting the wiper device on a chassis of a vehicle. It has numerous components, so that many manufacturing and mounting steps are needed. In order to reduce the weight of the wiper device, hollow profiles or so called tubular plates are used as supports.
Such tubular carriers disclosed for example in the German patent document DE 29 20 899 C2, in which the tubular members with corresponding projections are inserted in the hollow profile. The projections are located at least partially on the walls of the support and have at least one recess in which the portions of the support are pressed, to provide a form-locking connection between the support and the tubular members. Wiper bearings are released in the pipe. This approach reduces the number of parts when compared with the screw connection. However, the joining process still requires numerous prefabricated components with many manufacturing steps. This makes more expensive the bearing hold and logistics. Furthermore, the massive projections have a substantial weight despite the recesses.
A method of converting tubular members into work pieces is disclosed in the magazine "Werkstatt and Betrieb", Carl Hanser Verlag, Munhen, 1995, pages 812-815 and the reprint from the publication "Metallumformtechnik", Claus Dannert Verlag, 1994, under the title "Prazisions-Werkstucke in Leichtbauweise, hergestilt durch lnnenhochdruck-Umformen". This method is used first of all for vehicle industry and operates with high pressures.
The tubular element to be deformed is placed in a subdivided tool, in which the desired workpiece shape is produced. The tool which is mounted in a press is closed by a vertically operating press plunger. The tubular element ends are closed by the closing tool, through which a pressure medium is supplied to press the tubular walls against the inner tool mold. An axial pressure is applied by the horizontally operating plungers on the tube, which is superimposed with inner pressure. Thereby the material which is required for the deformation is taken not only from the wall thickness of the tubular element, but is also provided by the shortening of the tube. The closing tools are axially hollowed during the deformation.